Needle based helical coil safety device

ABSTRACT

The present disclosure describes anti-needle stick safety mechanism that is passively activated during the normal course of giving an injection. In one embodiment, the device includes a spring member coupled at a proximal end to a needle member and at a distal end to a needle cover. The passive activation of the device is triggered when the needle is inserted to a minimum depth into the patient&#39;s tissue to unleash the force of a compressed spring to urge a needle cover towards the distal end of the needle. As the needle is withdrawn from the tissue, the needle cover advances to the end of the needle and as it partially clears the end of the needle, it adopts an orientation that prevents the needle tip from re-emerging from the needle cover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/101,585filed May 5, 2011, now U.S. Pat. No. 8,858,509, which claims the benefitof U.S. provisional application Ser. No. 61/331,757 filed May 5, 2010,both of which are incorporated by reference herein.

FIELD

The embodiments provided herein relate generally to syringe systems foradministering therapeutic agents to patients. More specifically, theembodiments relate to a needle stick safety device.

BACKGROUND

Injecting medicine directly into tissue through a hollow bore needleremains a preferred method of administration many drugs. Once a needlehas been used to give an injection, contact with the needle can transmittissue borne diseases to health care workers, patients, and anyone elsewho could come in contact with the used injection device. If thesubsequent contact also involves a puncture of the skin, diseasetransmission becomes much more likely.

Accordingly, an improved safety device mountable on a needle device thatfacilitates prevention of needle stick injuries by way of a mechanismthat covers and isolates the needle after injection is desirable.

SUMMARY

The embodiments presented herein are directed to preventing needle stickinjuries by way of a mechanism that covers and isolates the needle afterinjection. The subject anti-needle stick safety mechanism is passivelyactivated during the normal course of giving an injection. In oneembodiment, the device includes a spring member coupled at a proximalend to a needle member and at a distal end to a needle cover. The springmember is expandable from a compressed state to a natural expanded stateto cover the needle and orient the needle cover to isolate the needletip.

The passive activation of the device is triggered when the needle isinserted to a minimum depth into the patient's tissue. When this hasoccurred, the force of a compressed spring is unleashed urging a needlecover towards the distal end of the needle. As the needle is withdrawnfrom the tissue, the needle cover advances to the end of the needle andas it partially clears the end of the needle, it adopts an orientationthat prevents the needle tip from re-emerging from the needle cover.

Other systems, methods, features and advantages of the exampleembodiments will be or will become apparent to one with skill in the artupon examination of the following figures and detailed description.

DESCRIPTION OF THE DRAWINGS

The details of the example embodiments, including structure andoperation, may be gleaned in part by study of the accompanying Figures,in which like reference numerals refer to like parts. The components inthe Figures are not necessarily to scale, emphasis instead being placedupon illustrating the principles of the invention. Moreover, allillustrations are intended to convey concepts, where relative sizes,shapes and other detailed attributes may be illustrated schematicallyrather than literally or precisely.

FIG. 1 shows an exploded isometric view of an embodiment of ananti-needle stick safety device.

FIG. 2 shows an assembled isometric view of the anti-needle stick safetydevice in a pre-injection or retracted state.

FIG. 3 shows an exploded isometric view of the anti-needle stick safetydevice ready for assembly with a syringe with a Luer fitting.

FIG. 4 shows an assembled isometric view of the anti-needle stick safetydevice assemble with a syringe with a Luer fitting in a pre-injection orretracted state.

FIG. 5 shows an assembled isometric view of the anti-needle stick safetydevice in a post-injection safety configuration or extended (needleshielded) state.

FIG. 6 shows a sectional view of the anti-needle stick safety device ina post-injection safety configuration or extended (needle shielded)state.

FIG. 7 shows an isometric sectional view of an embodiment of a needletip cover.

FIG. 8 shows an isometric view of the needle tip cover from the proximalend of the needle tip cover.

FIG. 9 shows a sectional view of an embodiment of a Luer needle.

FIG. 10 shows an orthogonal view from a proximal end of the Luer needleand needle tip cover in an assembled configuration ready to trigger thesafety mechanism after injection of a medication into tissue of apatient. The helical coil spring has been removed from the Figure forclarity.

FIG. 11 shows an orthogonal view from a proximal end of the Luer needleand needle tip cover in an assembled configuration just after injectionof a medication into tissue of a patient and the safety mechanism hasbeen triggered. The helical coil spring has been removed from the Figurefor clarity.

FIG. 12 shows an orthogonal view of an embodiment of an assembledone-piece anti-needle stick safety device in a pre-injection orretracted state.

FIG. 13 shows a sectional view of the one-piece anti-needle stick safetydevice shown in FIG. 12.

FIG. 14 shows a sectional view of the one-piece anti-needle stick safetydevice shown in FIG. 12 with the needle embedded in tissue.

FIG. 15 shows a sectional view of the one-piece anti-needle stick safetydevice shown in FIG. 12 with the needle withdrawn from the tissue andthe device in a needle-stick safety configuration with the integralneedle tip cover covering the distal end of the needle.

It should be noted that elements of similar structures or functions aregenerally represented by like reference numerals for illustrativepurpose throughout the figures. It should also be noted that the figuresare only intended to facilitate the description of the preferredembodiments.

DETAILED DESCRIPTION

Each of the additional features and teachings disclosed below can beutilized separately or in conjunction with other features and teachingsto produce systems and methods to facilitate needle stick prevention.Representative examples of the present invention, which utilize many ofthese additional features and teachings both separately and incombination, will now be described in further detail with reference tothe attached drawings. This detailed description is merely intended toteach a person of skill in the art further details for practicingpreferred aspects of the present teachings and is not intended to limitthe scope of the invention. Therefore, combinations of features andsteps disclosed in the following detail description may not be necessaryto practice the invention in the broadest sense, and are instead taughtmerely to particularly describe representative examples of the presentteachings.

Moreover, the various features of the representative examples and thedependent claims may be combined in ways that are not specifically andexplicitly enumerated in order to provide additional useful embodimentsof the present teachings. In addition, it is expressly noted that allfeatures disclosed in the description and/or the claims are intended tobe disclosed separately and independently from each other for thepurpose of original disclosure, as well as for the purpose ofrestricting the claimed subject matter independent of the compositionsof the features in the embodiments and/or the claims. It is alsoexpressly noted that all value ranges or indications of groups ofentities disclose every possible intermediate value or intermediateentity for the purpose of original disclosure, as well as for thepurpose of restricting the claimed subject matter.

Turning to the figures, the embodiments presented herein are directed topreventing needle stick injuries by way of a mechanism that covers andisolates the needle after injection. The subject anti-needle sticksafety mechanism is passively activated during the normal course ofgiving an injection so that the user does not need to learn or rememberany extra operational steps. This contrasts with manually activateddevices, which require extra actions such as manually extending a shieldover the needle after the injection is given. Although the injectionsdescribed herein concern those done with a Luer needle, it is understoodthat the needle could also be of the staked variety, where the needle ispre-attached to the syringe or whatever injection device is being used.It could also be miniaturized to fit underneath the needle shield usedwith staked needles.

The subject anti-needle stick safety device 10 is depicted in anexploded orientation in FIG. 1 and in an assembled orientation in FIG.2. The passive activation of the device 10 is triggered when the needle301 is inserted to a minimum depth into a patient's tissue. When thishas occurred, the force of a compressed spring 20 is unleashed urging aneedle cover 40 towards the distal end of the needle 301. As the needle301 is withdrawn from the tissue, the needle cover 40 advances to theend of the needle 301 and as it partially clears the end of the needle301, it adopts an orientation that prevents the needle tip fromre-emerging from the needle cover 40. The details of this mechanism willbe described below.

In one embodiment as depicted in FIG. 1, the device comprises three maincomponents comprising a Luer needle 30, a spring member 20, and a needlecover 40. Referring to FIGS. 1 and 7, the shaft 301 of the Luer needle30 is a standard type of hollow bore needle used for giving injection ofmedications or the removal of body fluids from patients or animals. Thedistal end 306 of the shaft has a beveled surface suitable forpenetration into tissue. The Luer needle 30 has at its proximal end aLuer fitting 305, which is a standard medical industry fluid transferattachment for syringes, valves, etc. A pair of mounting pins 303 usedto mount the spring member 20 extend in opposite directions from theLuer fitting 305. A pair of latch arms 302 having recesses 304 used toretain the needle tip cover 40 in a pre-injection state extend from aneedle shaft mounting base 307.

As shown, the spring member 20 is preferably a flat helical spiral coilspring. The spring member 20 is preferably formed from a thin stainlesssteel OR nitinol metal sheet, preferably about 0.003 inches thick,having a high tensile strength so that it can sustain high strainswithout permanently deforming. A helical spiral coil spring member 20 ismade with a thin portion of steel stamped into the shape shown inFIG. 1. The central part is wound tightly such that its naturalconfiguration is an elongated helix with wide walls, which form acontinuous covering protecting the needle 301 inside from potentiallycontacting and contaminating health care providers, etc.

The needle tip cover 40 can be attached to the distal coils 201 of thehelical spiral coil spring 20 using a press fit arrangement, mountingpins as shown on the Luer needle 30, glue, or a spot weld operation. Itis also possible that needle tip cover 40 could be integrally formedfrom the geometry of the distal coils 201 of the helical spiral coilspring 20 by way of a progressive die manufacturing process to form acup shape at the distal end of the coil spring 20.

As depicted, the proximal coils 203 include one or more mounting holes202 formed therein to engage the mounting pins 303 on the Luer needle30. Preferably the mounting pins 303 press fit into the mounting holes202 to couple the helical spiral coil spring 20 to the Luer needle 30.

FIG. 2 depicts the device 10 in the assembled configuration and ready tobe attached to a syringe in preparation for giving an injection. Asdepicted, the needle tip cover 40 is in a first, retracted positionmounted along the needle shaft 301 of the Luer needle 30 and the helicalspiral coil spring 20 is compressed.

A syringe 50 with a Luer fitting 501 is depicted in FIG. 3. Prior to usein an injection, the Luer fitting 305 of the Luer needle 30 of theanti-needle stick safety device 10 is coupled to the Luer fitting 501 ofthe syringe 50, as shown in FIG. 4.

As depicted in FIGS. 1, 5 and 6, the distal coils 201 of helical spiralcoil spring 20 are oriented at an angle to the helical spiral coilspring 20 axis and the shaft of needle 301. The needle tip cover 40 isattached to the distal coils 201. The distal coils 201 allow the needletip cover 40 to elastically align to the shaft of needle 301 when thehelical spiral coil spring 20 and needle tip cover 40 are fullyassembled as shown in FIG. 2. When the needle tip cover 40 is positionedbeyond the tip 306 of needle 301 as shown in FIGS. 5 and 6, the elasticforce of the distal coils 201 urge the needle tip cover 40 to becomeangled with respect to the shaft of the needle 301 in a safetyconfiguration.

As depicted in FIGS. 5 and 6, when the anti-needle stick safety device10 is triggered as discussed below, the helical spiral coil spring 20 isextended to its natural configuration forcing the needle tip cover 40 topartially clear the distal tip 306 of needle 301 and allowing it tocover and isolate the tip 306 of needle 301. The needle tip cover 40 isat an angle to the shaft of needle 301 thus jamming the needle shaft 301against a locking hole 402 to secure it to prevent relative motion ofthe needle tip cover 40 with respect to the needle tip 306.

The details of the needle tip cover 40 are shown in FIGS. 7 and 8. Asdepicted, the needle tip cover 40 is generally cup shaped with acylindrical side wall or body 405 and an inwardly chamfered or concavedistal surface 406 (in the proximal direction) with a distal hole 401 atthe center of the distal surface 406. The shape of the distal hole 401and surrounding surface 406 allow passage of the needle shaft 301 andthe collection of any body fluids at a recessed point to avoid possiblecontact with health care providers during withdraw of the needle 301.The concave surface 406 is projected to the interior of the needle tipcover 40 as can be seen in the sectional view of FIG. 7. As the tip 306of the needle 301 moves proximally with respect to the needle tip cover40 and as the needle tip 306 clears the proximal edge of the distal hole401, the needle tip cover 40 can become angled with respect to the axisof the needle shaft 301 allowing the tip 306 of the needle 301 to bedirected away from the distal hole 401. The locking hole 402, which isformed in a locking arm 404, is in substantial axial alignment with thedistal hole 401. As the needle tip cover 40 becomes angled with respectto the axis of the needle shaft 301, the locking hole 402 jams againstthe needle shaft 301 and secures the needle tip cover 40 relative to theneedle tip 306.

The needle tip cover 40 has one or more latches 403 that engage with oneor more recesses 304 in one or more needle cover latch arms 302 shown inFIGS. 1, and 6 through 11. The latches 403 resist distal movement of theneedle tip cover 40 in response to the distally directed force of thehelical spiral coil spring 20 when the latches 403 are engaged with thelatch recesses 304 as shown in FIG. 10. The lateral surfaces of thelatches 403 engage with corresponding lateral surfaces of the latchrecesses 304 of the latch arms 302 to prevent clockwise rotation of theneedle tip cover 40 (clockwise as viewed from the proximal end of thedevice looking in a distal direction). During assembly, the needle tipcover 40 is pushed down the shaft of the needle 301 and is given aslight counter clockwise (as viewed from the proximal end) rotationaltwist against the rotational elasticity of the helical spiral coilspring 20 before the distal surfaces of the latches 403 are allowed tocome to rest against the proximal edges of the latch recesses 304. Thehelical spiral coil spring 20 distally directed axial force is held incheck by the mating distal surfaces of the latches 403 and proximalsurfaces of latch recesses 304. The stored rotational energy of thehelical spiral coil spring 20 as a consequence of the twist impartedduring assembly maintains a clockwise directed rotational torque to theneedle tip cover 40 (shown by the arrow in FIG. 8) urging the latches403 into the latch recesses 304. More importantly, when the needle tipcover 40 is moved proximally during contact with injection site tissue,the needle tip cover 40 will rotate causing the latches 403 to unseatand move away from the latch recesses 304. At this point the safetymechanism 10 has been triggered. As the needle tip cover 40 begins tomove distally as the needle 301 is withdrawn from the patient, thelatches 403 clear the latch recesses 304 allowing the needle tip cover40 to move to the distal end of the needle 301 in response to the forcestored in the helical spiral coil spring 20.

The entire safety device 10 would normally be packaged in a sterileenclosure, which has not been shown for clarity. A typical sequence ofsteps for using the device 10 would be for a health care provider orself-administrating patient to remove the device 10 from the sterileenclosure and attach the device 10 to the Luer fitting 501 of thesyringe 50 (FIGS. 3 and 4) or other device containing the prescribedmedication. After locating and preparing the injection site, the needle301 would be pushed into the tissue. The initial position of needle tipcover 40 on the shaft of the needle 301 is such that as the needle 301is advanced into the tissue, the tissue pushes against the needle tipcover 40, which disengages the needle tip cover latches 403 from theneedle latch recesses 304 and allows the helical spiral coil spring 20to urge the needle tip cover 40 towards the tip 306 of the needle 301.The force of the spring 20 is small enough to not interfere with theuser positioning the needle 301 to the appropriate tissue depth. Afterthe medication has been dispensed (or body fluid withdrawn), the userpulls the device 10 away from the tissue and under the force of thehelical spiral coil spring 20, the needle tip cover 40 continues to restagainst the tissue as the needle 301 is withdrawn. With further withdrawof the needle 301, the needle tip 306 emerges from the tissue andeventually the needle tip cover 40 is pushed beyond the tip 306 of theneedle 301 so that the needle tip 306 clears the confines of the needletip cover distal hole 401 (FIG. 6). At this point, the elastic force ofthe distal coils 201 angles the needle tip cover 40 with respect to theneedle shaft 301 and the needle tip cover locking hole 402 engages theshaft 301 of the needle. Consequently, the tip 306 of the needle 301 ispointed away from the needle cover distal hole 401 and the locking hole402 has engaged the needle shaft 301 with the edges of the proximal anddistal surfaces of the locking hole 402.

The needle tip cover locking hole 402 is preferably made of a materialthat is harder than the needle shaft 301 and is formed with crisp edgesand a diameter such that when the tip cover 40 is put at an angle afterclearing the needle tip 306, the locking hole 402 is able to bite intothe needle shaft 301 with enough force to prevent movement of the tipcover 40 relative to the needle shaft 301. The main purpose of thelocking hole-shaft 402-301 engagement is to prevent the needle tip cover40 from being pushed distally off the needle tip 306 since proximallydirected forces, which would be typical during a needle stick accident,would tend to push the tip 306 of the needle 301 into the distalexterior comer of the needle tip cover 40 where it will be stablycontained. The needle tip cover 40 is preferably made of a material thatis hard enough to prevent the needle tip 306 from penetrating its wall.

Referring to FIGS. 12-15, an alternative embodiment comprising aone-piece anti-needle stick safety device 11 is shown. As depicted, theone-piece anti-needle stick safety device 11 comprises an integralneedle tip cover 213 that could be formed from the distal material ofthe helical spiral coil spring 21 as by a progressive die manufacturingmethod. The proximal attachment of the helical spiral coil spring 21 tothe Luer needle 30 is shown with an inwardly bent proximal coil 215 witha proximal locking hole 217. As with the other applications of a lockinghole described herein, the proximal locking hole 217 would be sized soas to grasp the needle shaft 301 when the proximal locking hole 217 wasangled from the perpendicular with respect to the axis of the needle301. The inwardly bent proximal coil 215 would maintain an angle greateror less than perpendicular to the needle shaft 301 so that the proximallocking hole 217 secured the proximal end of the helical spiral coilspring 21 to the needle 301. This attachment, rather than attaching theproximal end of the helical spiral coil spring 21 to the Luer needle 30as shown in FIG. 2, could be used for placing the entire anti-needlestick safety device 21 underneath a needle shield, which is used to forma seal between the tip of the needle and the proximal area of the needlein order to keep this area sterile after a sterilization procedure suchas treatment with ethylene oxide (eto).

At the distal end of the helical spiral coil spring 21 is an inwardlybent first distal coil 214 with a first distal locking hole 216. In theassembled configuration, inwardly bent first distal coil 214 holds thefirst distal locking hole 216 at a non-perpendicular angle to thelongitudinal axis of the needle 301. In this orientation, the firstdistal locking hole 216 holds the position of the integral needle tipcover 213 on the needle 301 against the force of the spring 21 at aposition that exposes the needle 301 for insertion into tissue T (FIG.14). Located distally to the inwardly bent first distal coil 214 withthe first distal locking hole 216 is a second bent distal coil 210inwardly bent at a second direction relative to the inwardly bent firstdistal coil 214 as shown in FIG. 13. The second bent distal coil 210includes a second distal locking hole 218. Inwardly bent first distalcoil 214 and second bent distal coil 210 have a spring bias between themthat attempts to increase the angle between each other and maintainnon-perpendicular orientations of their respective locking holes 216 and218 to further increase the grasp they have on the needle. With thisinternal spring bias, the integral needle tip cover 213 can bepositioned and held for the life of the product at a desired positionalong the length of the needle 301 with the helical spiral coil spring21 under compression. With a proximally directed force from the tissue Tduring needle insertion, directed against the integral needle tip cover213 (FIG. 14) the spring bias between the inwardly bent first distalcoil 214 and second bent distal coil 210 is overcome, reducing the anglebetween them and causing the locking holes 216 and 218 to have an anglewith respect to the axis of the needle 301 close to perpendicular,thereby releasing their grasp on the needle 301 and allowing theintegral needle tip cover 213 to slide along the needle shaft. As theneedle 301 is withdrawn from the tissue T, the integral needle tip cover213 slides to the end of the needle 301 (FIG. 15). At this point, theinwardly bent first distal coil 214 has resumed its non-perpendicularorientation with respect to the axis of the needle 301 thereby allowingthe first distal locking hole 216 to engage the shaft of the needle 301.The tip 306 of the needle 301 has become positioned proximal to theopening of the integral needle tip cover 213 and as the second distallocking hole 218 clears the tip 306 of the needle 301 (shown partiallyprogressed in FIG. 15), the spring bias of the second bent distal coil210 displaces the integral needle tip cover 213 so that the needle tip306 is not aligned to the distal hole 220 and is prevented fromre-emerging from the integral needle tip cover 213.

For the sake of visualization, the integral needle tip cover 213 and thedistal coils of the helical spiral coil spring 214 and 210 have beenshown with gaps between the components, which would be normallyminimized to provide for maximum isolation of the contaminated needlefrom the external environment.

While a typical coil spring made with round wire could provide theelastic force for moving the needle tip cover to the end of the needle,it would potentially allow exposure of biological contaminants on theshaft of the needle to health care workers via the spaces between coils.Furthermore, it is desirable to make the safety device as small asreasonable possible so that storage and hazardous disposal volumes areminimized. Since standard coil springs have solid heights, which aresignificant compared to their extended lengths, they could necessitatethe use of a longer, and therefore, more flimsy, needle than wouldnormally be used. It is desirable, therefore, to have a spring, such asthe helical spiral spring herein depicted, that adopts the shortestcompressed length for a given amount of elastic travel and that forms acontinuous cylindrical structure in the elongated state to prevent thetransfer of contaminants from the needle to the health care environment.

While the invention is susceptible to various modifications, andalternative forms, specific examples thereof have been shown in thedrawings and herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but to the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the appended claims.

The invention claimed is:
 1. A syringe and safety device comprising asyringe body with a needle hub extending from a distal end and a needleshaft extending from the needle hub, the needle hub having a first latchmember, a helical spiral coil spring coupled at a proximal end to theneedle hub, and a needle cover coupled to the helical spiral coil springat a distal end and slidably receivable over the needle shaft, theneedle cover having a second latch member cooperatable with the firstlatch member to retain the needle cover in a first retracted positionalong the needle shaft, wherein when the needle cover is retained in thefirst retracted position the helical spiral coil spring is biased tourge the needle cover to move to a second position partially beyond adistal tip of the needle shaft and oriented at an angle relative to alongitudinal axis of the needle shaft preventing the needle shaft fromre-emerging from the needle cover, axis of the needle shaft preventingthe needle shaft from re-emerging from the needle cover, wherein thehelical spiral coil spring is biased to axially and rotationally urgethe second latch member into engagement with the first latch member toretain the needle cover in the first retracted position, wherein theneedle cover is moveable proximally in an axial direction from the firstrefracted position to passively disengage the second latch member fromthe first latch member due to a proximal force exerted on the needlecover from contact with a patient's tissue during insertion of theneedle shaft into the patient's tissue and upon proximal movement of theneedle cover from the first retracted position, the spring being biasedto rotationally urge the second latch member away from the first latchmember to avoid reengagement of the first and second latch members upondistal movement of the needle cover as the needle shaft is withdrawnfrom the patient.
 2. The syringe and safety device of claim 1 whereinthe needle cover has a distal surface that is inwardly chamfered in theproximal direction and a distal hole in the center of the distalsurface.
 3. The syringe and safety device of claim 2 wherein the needlecover further comprises a locking hole aligned axially with the distalhole.
 4. The syringe and safety device of claim 3 wherein needle shaftis misaligned with the distal hole in the distal surface when the needlecover is oriented in the second position partially beyond the distal tipof the needle shaft.
 5. The syringe and safety device of claim 3 whereinthe edges of the locking hole bite into the shaft of the needle toprevent movement of the needle cover relative to the needle shaft whenthe needle cover is oriented at an angle relative to the longitudinalaxis of the needle shaft.
 6. The syringe and safety device of claim 1wherein the first latch member includes a recess engaged by the secondlatch member when the needle cover is retained in the first retractedposition.
 7. The syringe and safety device of claim 1 wherein the needlecover is integrally formed with the spring.
 8. The syringe and safetydevice of claim 1 wherein the spring includes one or more mounting holesformed in the proximal coils of the spring.
 9. The syringe and safetydevice of claim 7 wherein the needle includes one or more mounting poststo couple the spring to the needle.
 10. A method for performing aninjection using a passive anti-needle stick safety device and syringeincluding a syringe body with a needle hub extending from a distal endand a needle shaft extending from the needle hub, a helical spiral coilspring coupled at a proximal end to the needle hub, and a needle tipcover coupled to the helical spiral coil spring at a distal end, theneedle tip cover retained by cooperating latches on the needle hub andthe needle tip cover in a first retracted position wherein the needle isexposed beyond the needle tip cover, the helical spiral coil springbeing biased to axially and rotationally urge the cooperating latchesinto engagement to retain the needle tip cover in a first retractedposition and upon disengagement of the cooperating latches, urge a firstcooperating latch away from a second cooperating latch and the needletip cover towards a second extended position for covering and preventingthe needle from reemerging from the needle tip cover, the methodcomprising: inserting the needle shaft into a patient's tissue apredetermined distance thereby exerting a proximal force on the needletip cover from the patient's tissue causing the needle tip cover and afirst cooperating latch on the needle tip cover to move axially in theproximal direction relative to a second cooperating latch on the needlehub to passively disengage the first and second cooperating latches and,upon disengagement of the first and second cooperating latches, thehelical spiral coil spring causing the needle tip cover to rotate aboutthe needle hub and rotate the first cooperating latch relative to thesecond cooperating latch to avoid reengagement of the first and secondcooperating latches as the needle tip cover moves distally uponwithdrawal of the needle shaft from the patient's tissue; and after themedication is injected into the patient, withdrawing the needle from thetissue thereby allowing the spring to extend to cover the needle andurge the needle tip cover to the second extended position wherein theneedle is prevented from reemerging from the needle tip cover.
 11. Themethod of claim 10, wherein the needle is withdrawn from the patient asthe needle tip cover is extended partially beyond the tip of the needleand oriented at an angle relative to the longitudinal axis of the needleshaft.
 12. The method of claim 11, wherein the needle shaft ismisaligned with a distal hole in the needle tip cover preventing theneedle shaft from reemerging from the needle tip cover.
 13. The methodof claim 11, wherein the needle shaft is misaligned with a locking holepreventing relative movement between the needle tip cover and the needleshaft.
 14. The method of claim 10, wherein the first cooperating latchon the needle tip cover exerting a distal force and a rotational forceon the second cooperating latch extending from the needle hub when theneedle tip cover is held in the first retracted position.